EVANS Hydraulic red heads are manufactured with a thin layer of oil between two layers of 7 mil film for maximum durability. They feature a deep, powerful sound and minimal sustain typical of early 70s rock. Hydraulic heads are renowned for their ease of tuning, making them ideal for drummers who are not accustomed to tuning their heads, or who have a slightly temperamental drum set. EVANS Level 360 technology has been incorporated to extend the contact surface 360 degrees around the entire circumference of the drum.